1. Field of the Invention
The present invention relates to a plasma display device, and more particularly, to a plasma display device with a reduced cell space by providing a crosstalk shielding electrode.
2. Description of the Related Art
In general, a plasma display device includes at least a pair of electrodes and generates discharge by a voltage applied to the electrodes. Due to excellent display characteristics such as display capacity, brightness, contrast and view angle, much attention has been paid to plasma display devices as flat display panels having almost the same performance as cathode ray tubes.
A plasma display panel is largely divided into a direct current (DC) plasma display panel and an alternating current (AC) plasma display panel according to its operational principles. In the DC plasma display panel, all electrodes are exposed to a discharge space, in which charges migrate directly from/to corresponding electrodes. On the other hand, the AC plasma display panel has a structure in which at least one electrode is surrounded by a dielectric material, wherein charges do not directly migrate from/to corresponding electrodes and discharging is performed by the electrical field of wall charges. The DC plasma display panel adopts both a DC driving method by which the polarity of a driving voltage does not change, and an AC driving method by which the polarity of a driving voltage changes. However, the AC plasma display panel adopts only the AC driving method.
Meanwhile, a plasma display panel is divided into a cross discharge type and a neighboring discharge type according to the discharge mechanism. The cross discharge type plasma display panel includes a scanning electrode opposite an address electrode, generates an addressing discharge therebetween and the addressing discharge is sustained by a sustaining discharge. The neighboring discharge type plasma display panel includes a scanning electrode and a common electrode which face an address electrode, and generates an addressing discharge between the address electrode and the common electrode and a sustaining discharge between the scanning electrode and the common electrode.
Referring to FIGS. 1 and 2, an example of a neighboring discharge type plasma display device will be described briefly. The plasma display device includes address electrodes 11 formed on a rear substrate 10 in a predetermined pattern, and a dielectric layer 12 covering the address electrodes 11 and the rear substrate 10. A partition 13 formed on the dielectric layer 12 maintains a discharge distance, and a fluorescent layer 17 is formed between neighboring partitions 13. A front substrate 16 is installed over the rear substrate 10, and a scanning electrode 14 and a common electrode 15, perpendicular to the address electrodes 11, are alternately formed on the bottom of the front substrate 16. A dielectric layer 18 is coated on the front substrate 16 and the scanning and common electrodes 14 and 15. A protective film 20 is coated on the dielectric layer 18. A predetermined discharge gas is injected to a discharge space S between the front substrate 16 and the rear substrate 10.
Referring to FIG. 2, if a voltage is applied to the respective electrodes, ions of the discharge gas accumulate on the dielectric layer 12. A trigger discharge is generated between the address electrode 11 and the common electrode 15 by the accumulated ions, and charged particles are formed on bottom surface of the dielectric layer 18 of the front substrate 16. At this time, according to image signals, a sustaining discharge is generated in the discharge space S by a predetermined voltage V applied between the scanning electrode 14 and the common electrode 15. Then, the fluorescent material is excited by the plasma formed in the discharge gas to then emit light.
Referring to FIG. 3, the electrodes 14 and 15 are repeatedly formed with a constant cell pitch CP on the front substrate 16. The cell pitch CP is a constant value as a design factor determined in consideration of resolution in a given screen size. Thus, in order to improve discharge efficiency or the brightness under a given cell pitch CP, the electrode width EW must be increased. However, since the cell pitch CP is constant, increasing the electrode width EW requires a reduction in the cell space CS. Current having pulses of opposite polarities is applied to the electrodes 14 and 15 by a circuit equivalent to one as shown in FIG. 4. In this case, if the cell space CS is small, a crosstalk discharge as well as a normal discharge is generated between the electrodes 14 and 15 positioned in the adjacent cells as shown in FIG. 5. Thus, since the reduction in the cell space CS cannot exceed a certain limit, the electrode width EW must be unavoidably reduced, which results in the reduction in the light emission area in the discharge cell to thereby decrease brightness. Also, the plasma display requires a high voltage for normal discharge. Further, since the concentration of electrical fields is lowered during discharge, which degrades the overall discharge efficiency.